Why we don't talk about such things... Because of the prussian education, results based schooling, people are ego identified with their beliefs.
Through the schooling process, these beliefs are imposed as facts.

So, if you want to have a holiday ending shouting discussion, start talking about politics. Thus, the women folk shut it down. Women care much more about harmony then they do about politics or what it entails.

This is why these topics are verboten around the holiday table.